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Networks - Coggle Diagram
Networks
Network Hardware
Router
It is responsible for forwarding data packets between different computer networks uses various protocols such as IP.
Hub
A hub acts as a point that can connect all devices on a network together. A hub receives data from computers connected to it. When a hub receives a frame it amplifies it and then transfers it to a destination PC by broadcasting it to all other devices on the network.
Switch
A switch performs a similar role as a hub. However switches tend to be more expensive as they perform an additional task. In a hub the data frames are broadcast to all devices but in a switch they are only sent to the devices it needs to. Less data on network so data transfers faster.
Network Interface Card
The NIC stores the information that identifies an individual device on a network, the MAC address.
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Protocols
email protocols
IMAP: Internet Messaging Access Protocol. This method of receiving emails is more suited to users who have multiple devices. This is because it maintains a copy of the email on the server until it is deleted by the user. This is a receiving protocol.
POP: Post Office Protocol. POP receives and holds emails until they are picked up by a user. When the user checks their email it is downloaded from the server and then deletes it from the server. The email is then only available locally on the device which the user downloaded it to. This is a receiving protocol.
SMTP: Simple Mail Transfer Protocol. This protocol allows for emails to be sent between email servers. This is particularly relevant when the server and recipient have different email providers . This is a sending protocol.
Web protocols
HTTP: Hypertext transfer protocol. Requests that the web server transmits the requested web page to the viewer's web browser.
HTTPS: Hypertext transfer protocol secure. Works in a similar way to HTTP but as this data is transmitted it is encrypted. This is becoming the most common protocol on the world wide web as it gives users peace of mind when entering financial details such as banking or debit/credit card details.
TCP/IP
TCP: Transmission control protocol. TCP is responsible for how messages are broken into packets and reassembled at the destination. TCP is also responsible for checking for errors and if necessary resends lost packets.
IP: Internet protocol. The IP protocol allows for a device to be identified on the internet and allows for appropriate packet routing.
Every computer in the world has a unique IP address. This IP can be changed be the user or automatically depending on the situation in which it is being used; mobile devices tend to have dynamic IP addressing meaning that it can change.
The current system is known as IPv4. It takes an address that is made up of 4 values up to 255 (8 bits). Example of an IPv4 address- 65.123.54.254
It is anticipated that we will run out of possible combinations for IPv4 as there may be as many as 30 billion devices in the world. To deal with more devices a new system called IPv6 has been developed. IPv6 128 bits long which are arranged in eight groups of sixteen bits. Each group is four hexadecimal values. Example of an IPv6 address- AD34:65AD:1111:04DC:3456:0000:DF34:34ED.
A protocol is an agreed set of rules. To allow computers to communicate there are a range of protocols to allow for certain applications. Without these agreed rules for transmissions it would require everyone to have the same software and hardware around the world!
Network topologies
mesh
In this type of network each node is connected to every other. To connect to the internet only one of the nodes needs to be connected to a modem, this connection is then shared across the rest of the network.
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Advantages: Using a full mesh network allows for data frames (similar to packets) to be sent via the quickest route. This network is also self healing.
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Layers
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The Network/Internet layer. This attaches the IP address of the sender so that computer that receives it knows where it has come from. It also attaches the address of the host and the destination IP address.
The Application Layer- This encodes the data that is being sent so that it will be understandably by the recipient. This might involve formatting data and adding a header according to the protocol such HTTP or FTP.
The Link layer. This attaches the MAC addresses of the sender and the recipient allowing for the packet to be sent to a specific device on a LAN.
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encryption
Encryption is a process stat is designed to protect data from being hacked or accessed illegally by scrambling the information.
Symmetric encryption uses a key which can be a combination of letters, numbers and other characters. A single key is used to encrypt and decrypt the message.
The more secure version is to use Asymmetric encryption or know as Public Key Encryption (PKE). With this type of encryption a private and a public key is needed.
Key terms:
Plaintext- The original, unencrypted message Ciphertext- The encrypted message Encryption- the process of converting from plaintext to ciphertext
Key- a sequence of numbers and letters and other characters that are used to decrypt or encrypt
Encryption algorithm- the method used for the encryption.
LAN and WAN
Local Area networks usually cover a relatively small geographic area. They consist of a single site such as a school or home.
Wide Area Networks (WAN) cover a large geographical area, the most famous being the internet.
Mac addressing
Each device that connects to a network has a Network Interface Card (NIC). Each NIC has it's own Media Access Control address (MAC address).
A MAC address cannot be changed, it is unique to that device. A MAC address is a 48 bit address written in Hexadecimal.
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